Water valve for rock drills



y 1969 c. G. B. EKWALL 3,442,289

WATER VALVE FOR ROCK DRILLS,

Filed May 16, 1967 Sheet 24 44 35 36 5:4 Fig-30 35" 25 3332 37 INVENTOR.

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May 6, 1969 C. G. B. EKWALL Filed May 16, 1967 Sheet 2 of 2 F 55 Li L f? 36 INVENT Cu.R\ Gtis'i'aBcanhoRd EK United States Patent 3,442,289 WATER VALVE FOR ROCK DRILLS Carl Giista Bernhard Ekwall, Nacka, Sweden, assignor to Atlas Copco Aktiebolag, Nacka, Sweden, a corporation of Sweden Filed May 16, 1967, Ser. No. 638,976

Claims priority, application Sweden, May 18, 1966,

6,874/ 66 Int. Cl. F16k 11/22 U.S. Cl. 137-594 8 Claims ABSTRACT OF THE DISCLOSURE A water valve with controls therefor is provided for rock drills which operates in conformity with the throttle valve operating the rock drill so that the water valve moves in stepwise fashion from a partly open position to an open to a closed position corresponding to the movement of the throttle valve, and with the water valve having dual pneumatic servo motors for the operation thereof. With such an arrangement, the amount of flushing water admitted to the rock drill corresponds to the action of the rock drill during, for example, collaring or hole starting operations which normally are performed with the throttle valve in a partly open position, thus restricting the water flow to the drill steel and increasing the visibility of the collaring point during this preliminary operation.

A rock drill with inlet passages for conducting respectively compressed air and flushing water thereto is provided with a throttle valve and a water valve in respectively the air passage and the water passage thereof with both valves movable between closed, partly open and open positions for corresponding stepwise control of the amount of compressed air and flushing water admitted to the rock drill, said water valve having a pair of servo pistons in engagement therewith which are controlled pneumatically by the throttle valve such that one piston moves the water valve to partly open position when the throttle valve is moved to partly open position and the other piston moves the water valve to open position when the throttle valve is moved to open position.

This invention relates to a Water valve for compressed air operated rock drills and particularly to a water valve of the type actuated automatically by a servo motor, such as a piston motor, in dependance upon the position of ad justment of the throttle valve controlling the admittance of compressed air to the rock drill. In operation water valves of this type usually admit unrestricted miximum flow of flushing water to the rock drill and the flushing tube therein as soon as the impact motor of the rock starts operating even when the throttle is set in partly open position for reducing the active air pressure in the impact motor. During collaring or hole starting operations, which normally are performed with the throttle valve in such partly open position, this unrestricted flow creates disturbing splashing-around of the flushing water and reduces the visibility at the collaring point. Furthermore such water valves are often sensitive to water pressure fluctuations and may open unintentionally at pressure peaks which may be the cause of faulty functioning and blocking of the water valve operating means.

The primary object of the invention is to improve the collaring performance of the abovementioned type of water valves by automatic setting of the water valve to a position restricting the water flow to the rock drill when the throttle valve is adjusted to partly open position restricting the flow of compressed air to the rock drill. A further object of the invention is to eliminate the sensitivity of such water valves to water pressure fluctuation.

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For these and other purposes there is provided in a rock drill having inlet passages for conducting respectively compressed air and water to said rock drill, a water valve in said water inlet passage, movable between closed, partly open and open positions for corresponding stepwise control of the amount of flushing water admitted to said rook drill, a throttle valve in said air inlet passage movable between closed, partly open and open positions for corresponding stepwise control of the amount of compressed airadmitted to said rock drill, a pair of pneumatic servo motors in operative engagement with said water valve, and air passage means controlled by said throttle valve for causing one of said servo motors to move said water valve to partly open position when said throttle valve is moved to partly open position and the other to move said water valve to open position when said throttle valve is moved to open positon.

The invention will be described more in detail with reference to the accompanying drawings, in which FIG. 1 is a rear end view of the backhead of a rock drill incorporating a handle, a throttle valve and a water valve. FIG. 1a is a development of the outer surface of the throttle valve in FIG. 1. FIG. 2 is a sectional view on the line 2-2 in FIG. 1. FIG. 3a is a longitudinal sectional view through the water valve in the closed position thereof and viewed on the line 3a3a in FIG. 2. FIGS. 3b, 3c and 3d are three cross-sectional views chosen in axially spaced parallel relation to one another along the axis of the throttle valve in the closed position thereof respectively on the lines 3b-3b, 3c3c and 3d3d in FIG. 1. FIGS. 4aJ-4d are sectional views corresponding to FIGS. 3a-3d, but illustrating the partly open position of respectively the air throttle valve and the water valve, which position is used when a new hole has to be started during drilling. FIGS. Sa-Sb are sectional views corresponding to FIGS. 3w-3d but illustrating the respective valve sections when the throttle valve and the water valve are open.

In FIG. 1 the numeral 10 designates a backhead of a rock drill to which flushing water is supplied via a nipple 11 and compressed air via a nipple 12 from suitable supply hoses and sources, not shown. In line with the inner end of the nipple 12 there is turnable mounted in the backhead 10 a throttle valve 13. In conventional manner the throttle valve 13 includes a turnable plug actuatable by an outer lever 14 and an inner axial bore or air inlet passage 15 therein in communication with the nipple 12. The throttle valve 13 is provided with a radial port 16, which by means of the lever 14 can be turned from a closed position, FIG. 3b, to an open position, FIG. 5b, in which the port 16 registers with a passage 17 in the backhead 10 through which compressed air is conducted to the impact motor of the rock drill, not shown. In an intermediate position of the lever 14, corresponding to a partly open position of the throttle valve 13, there is established a restricted connection between the inlet passage 15 and the passage .17 via a throttling passage 18, FIG. 4b, through which the impact motor receives air at a restricted rate, i.e., at reduced air pressure for example for purposes of carrying out the collaring or starting of a new hole.

In the backhead 10 there is fixed a flushing tube 20 through which flushing water is conducted to the hOllOW drill steel, not illustrated. The flushing tube 20 extends from a bore 21, sealed by means of a threaded plug 22, and is supplied with water trough a side bore 23, extending from a transverse bore 24 parallel with the throttle valve 13 and coaxial with the inner end of the water nipple 11 and a water inlet passage 28 adjacent thereto. In the transverse bore 24 and an enlarged bore 25 adjacent thereto there is provided a water valve housing 26 in which a water valve 27 is slidably received. The water valve 27 is mounted to perform its closing movement oppositely to the direction of flow of the flushing water entering through the nipple 11. In the position depicted in FIG. 3a the water valve 27 is in the closed position thereof. In this position the water inlet passage 28 is kept closed by the water valve 27 blocking four radial passages 29 extending from the water inlet passage 28. The passages 29 are in communication with the transverse bore 24 and the side bore 23. As depicted in FIG. 4a the water valve 27 may take a partly open position for allowing flushing water to pass to the rock drill at a restricted rate for example allowing a flushing water flow of 2-2.5 litres per minute. In the partly open position the water valve 27 uncovers a single substantially radial passage 30, through which the inlet passage 28 is brought in communication with the side bore 23 and water tube 20. The water valve 27 may furthermore take an open position, FIG. a, in which the water valve 27 uncovers the single passage 30 as well as the four passages 29 which permits flow of flushing water to the rock drill at maximum rate, for example allowing a flow of 4.5 to 5 litres per minute to the side bore 23 and water tube 20.

The water valve 27 is of cylindrical plunger type provided with an internal chamber 33 which for the purpose of pressure equalization is in communication directly with the water inlet passage 28 via an axial front bore 34 centrally at its end face. The internal surface of the chamber 33 exposed to axial .pressure tending to move the water valve 27 to close position is provided by the interior abutments 35, 35" and the maximum cross sectional area of the chamber 33 adjacent abutment 35" is chosen sbustantially equal to the area of the end face of the water valve 27 in the inlet channel 28. Thus water pressure fluctuation in the valve channel 28 adjacent the water valve 27 will be equalized and will not set up any unbalanced axial forces in connection with said end face and the abutments 35', 35" tending respectively to open or to close the water valve 27 unintentionally. The rear end of the chamber 33 is closed by a shell 36 sealingly and slidably received in the chamber 35. The shell 35 bears against the valve housing 26 and axially directed water pressure forces acting thereagainst are thus taken up by said housing 26. A compression spring 37 is arranged between the bottom of the shell 36 and the abutment 35" biasing the water valve 27 to the closed position thereof, FIG. 3a.

The valve housing 26 is kept in position in the bores 24, 25 by means of a plug 38 threaded into the bore 25 and is subdivided in two coaxial aligned servo motor cylinders 26', 26" preferably made of stainless steel. An annular washer 39 is inserted axially between the cylinders 26', 26". The servo motor or actuating cylinder 26" has a cylinder bore 40 provided therein which an actuating servo piston 41 is slidably arranged, while the servo motor or auxiliary cylinder 26 has a cylinder bore 42 in which an auxiliary servo piston 43 is slidably arranged, the stroke of the auxiliary piston 43 in the auxiliary cylinder 26' being shorter when compared to the stroke of the actuating piston 41 in the actuating cylinder 26". The actuating piston 41 is integral with the water valve 27, whereas the auxiliary piston 43 is axially slidably mounted on the intermediate portion of the water valve 27 and abuts against an axial shoulder 44 provided intermediate the pistons 43, 41 on the water valve 27. The Water valve 27, its actuating piston 41 and the auxiliary piston 43 are preferably made of plastic material such as polypropylene.

For purposes of partly opening the water valve 27 the auxiliary cylinder 26' is pressurized to which end compressed air is conducted to the cylinder bore 42 to the end thereof opposite the washer 39 via a passage 46 from the throttle valve 13, the bore 25, and a peripheral groove 31 with radial bores in the cylinder 26. Such pressurization moves the auxiliary piston 43 in the cylinder bore 42 for a,full opening stroke to bear against the annular washer 39 and the water ,valve 27 is carried along by the shoulder 44 under compression of the spring 37 to the position depicted in FIG. 4a. For opening the water valve member 27 further, compressed air is also supplied for tpressurizing the actuating cylinder 26" from the throttle valve 13 via a passage 47 to the bore 25, a peripheral groove 32 with bores in the cylinders 26", and the space between the auxiliary piston 43 and the actuating piston 41. As a result the actuating piston 41 is moved to complete its full opening stroke away from the auxiliary piston 43 displacing the water valve 27 under further compression of the spring 37 to the position depicted in FIG. 5a.

For controlling the air supply to the passages 46, 47 the outer surface of the throttle valve 13, FIG. 1a is provided with an axial venting groove 50, which in the closed position of the water valve 27, FIGS. 3a-3d, connects both passages 46, 47 to the atmosphere via a peripheral groove 50' in the outer surface of throttle valve 13 and a venting passage 51 in the backhead 10. Furthermore the outer surface of the throttle valve 13 is provided with a pair of pressure grooves 52, 52" each communicating directly with the air inlet passage 15 in the throttle valve 13. The pressure grooves 52' 52" are spaced angularly in relation to the venting groove 50 and cooperate during turning motion of the throttle valve 13 each with one of the passages 46, 47 in such manner, that pressure groove 52' causes the water valve 27 to open partily for restricted delivery of flushing water, FIGS. 4a-4d, by connecting in a first position of adjustment of the throttle valve 13 the passage 46 to the air pressure in the air inlet passage 15 simultaneously with the passage 47 being kept closed and seperated from the pressure groove 52" in the throttle valve 13. Thereupon both pressure groove 52' and 52" together cause the water valve 27 to take the open position, FIGS. 5a-5d, by connecting in a second position of adjustment of the throttle valve 13 both passages 46, 47 to the air pressure in the air inlet passage 15.

The actuating cylinder 26" of the actuating piston 41 is provided with a radial bore 53 connected to the .peripheral groove. Furthermore, the end wall of the actuating cylinder 26" has a hole 54 bored axially therethrough and the plug 38 of the bore 25 is provided with a through bore 55. The bores 53-55 provide additional venting passages separate from the throttle valve 13 through which the actuating cylinder 26" and the passage 37 are vented to the atmosphere in the closed position as well as in the partly open position of the water valve 27. FIGS. 3a-3d and FIGS. 4a-4d, respectively. In the open position of the water valve 27, FIGS. 5a-5d, the bore 53 is closed by a sealing ring on the actuating piston 41, and the actuating piston 41 will thus remain pressurized in the actuating cylinder 26" by air entering through the passage 47 and perpheral groove 32 and keeping the actuating piston 41 at the end of the cylinder bore 40 opposite to the washer 39 When drilling of a hole is to be started by a eollaring operation, the lever 14 of the air throttle valve is turned from the closed position depicted in FIG. 3d to the partly open position depicted in FIG. 4b. The air inlet passage 15 of the throttle valve 13 is thus connected via the passage 18 with the passage 17 and the impact motor starts its operation. Simultaneously therewith, the pressure groove 52' registers with the passage 46, pressurizes the auxiliary cylinder 26' and causes movement of the auxiliary piston 43 to the annular washer 39. As a result the water valve 27 will be moved to partly open position for restricted flow of flushing water via the single bore 30, FIG. 4a, from the water inlet passage 28 to the side bore 23, the bore 21 and the flushing tube 20. The collaring operation can now be carried out under reduced flow of flushing water without excessive splashing-around of water. As soon as the drill-bit has proper guidance in the hole drilled in the rock, the lever 14 and the throttle valve 13 are turned to the open position depicted in FIG.

5d. Compressed air will now be freely admitted to the impact motor via the port 16 and the passage 17. Simultaneously both pressure groove 52', 52" are moved to supply both passages 46, 47 with compressed air pressurizing both cylinders 26', 26" and causing movement of the actuating piston 41 and the water valve 27 to the open position depicted in FIG. 5a.

When the drilling is terminated the lever 14 is turned back to the position depicted in FIG. 3d turning the throttle valve 13 to closed position. In such position both passages 46, 47 are vented via the grooves 50, 50 and the venting passages 51 to the atmosphere and the cylinders 26, 26" are thus relieved from pressure so that the spring 37 is relieved and is able to displace the water valve 27 to the closed position thereof depicted in FIG. 3a. When the throttle valve 13 during the closing movement thereof leaves the position depicted in FIG. 5d and reaches the partly open position depicted in FIG. 4d, the actuating piston 41 remains immovable in its position depicted in FIG. 5a because of the compressed air confined in the passage 47, in peripheral groove 32, and in the actuating cylinder 26" keeping the cylinder 26" pressurized. By such partial return movement, it is thus possi-ble to obtain unrestricted finishing by water while the impact mechanism is operating on a reduced air pressure. Such setting of the valves 13, 27 may be desirable during drilling through fissures and cracks in faulty rock.

'If reduction of the water flow is undesirable the auxiliary piston 43 can obviously be omitted during assembly. In such case the actuating piston 41 will serve as the sole servo motor or opening-means for the water valve 27 providing full opening of the water valve 27 by the actuating piston 41 as soon as the auxiliary cylinder 26 is pressurized via the passage 46.

What I claim is:

1. In a rock drill having inlet passages for conducting respectively compressed air and water to said rock drill, a water valve in said water inlet passage, movable between closed, partly open and open positions for corresponding stepwise control of the amount of flushing water admitted to said rock drill, a throttle valve in said air inlet passage movable between closed, partly open and open positions for corresponding stepwise control of the amount of compressed air admitted to said rock drill, a pair of pneumatic servo motors in operative engagement with said water valve, and air passage means controlled by said throttle valve for causing one of said servo motors to move said water valve to partly open position when said throttle valve is moved to partly open position and the other to move said water valve to open position when said throttle valve is moved to open position.

2. A water valve as set forth in claim 1 in which said servo motors are piston motors with the pistons thereof mounted in tandem on said water valve, the piston of said one servo motor having a smaller opening stroke in the cooperating cylinder thereof than the piston of said other servo motor in its cooperating cylinder, the full opening strokes of said pistons defining respectively said partly open and open position of said water valve, and said water valve being slidable in the opening direction thereof with respect to the piston of said one servo motor for permitting both said pistons to make full opening strokes under the control of said throttle valve and said air passage means.

3. In a rock drill having inlet passages for conducting respectively compressed air and flushing water to said rock drill, a water valve in said water inlet passage movable between closed and open positions for controlling the admission of flushing water to said rock drill, said water valve having an actuating piston connected thereto,

a throttle valve in said air inlet passage movable between closed, partly open and open positions for corresponding stepwise control of the amount of compressed air admitted to said rock drill, means for biasing said water valve to closed position, an actuating cylinder in said rock drill, slidingly housing said actuating piston therein for, moving the latter and said water valve to open position upon pressurization of said actuating cylinder by compressed air, cooperating air passage means in said throttle valve and said rock drill for so pressurizing said actuating cylinder in the open position of said throttle valve, and venting passage means in said rock drill and throttle valve for venting said actuating cylinder in the closed position of said throttle valve, said rock drill and water valve therein being characterized by an auxiliary piston in engagement with said water valve, an auxiliary cylinder in said rock drill slidingly housing said auxiliary piston therein for moving the latter and said water valve to partly open position upon pressurization of said actuating cylinder by compressed air whereby flushing water is conducted to said rock drill at a restricted rate, cooperating auxiliary air passage means in said throttle valve and said rock drill for so pressurizing said auxiliary cylinder in the partly open position of said throttle valve, and auxiliary venting passage means in said rock drill and throttle valve for venting said auxiliary cylinder in the closed position of said throttle valve.

4. A water valve as set forth in claim 3 in which said cylinders are mounted in said rock drill adjacent each other coaxially with said water valve and said pistons are mounted in tandem on said water valve.

5. A water valve as set forth in claim 4 in which said auxiliary piston is mounted slidably in intermediate position on said water valve and in abutting relation to a shoulder thereon for moving said water valve to said partly open position defined by the end of the stroke of the auxiliary piston in said auxiliary cylinder, said stroke being shorter than the stroke of said actuating piston in said actuating cylnder.

6. A water valve as set forth in claim 3 in which there are provided additional venting passage means in said rock drill connected to said actuating cylinder and to the atmosphere for venting said actuating cylinder in said closed as well as partly open position of said water valve.

7. A water valve of plunger type as set forth in claim 3 in which the plunger of said water valve has the end face thereof in constant communication with said water inlet passage, a pressure equalizing chamber in said water valve connected to said water inlet passage and having a cross sectional area substantially equal to the area of said end face, a shell tightly and slidably mounted in said chamber for closing the end thereof remote from said end face, and a surface in said rock drill for fixedly supporting said shell in said rock drill.

8. A water valve as set forth in claim 7 in which said biasing means is a spring disposed in said chamber and bearing against said water valve and shell.

References Cited UNITED STATES PATENTS 2,777,424 1/ 1957 Fuehrer 17377 3,032,068 5/1962 Bunyan 25163.4 XR

FOREIGN PATENTS 483,835 4/1938 Great Britain.

HENRY T. KLINKSIEK, Primary Examiner.

US. Cl. X.R. 

